Various types of compartmented truck bodies are used commercially as delivery vehicles and are provided with roll-up doors over each of the compartments of the truck. Such trucks are commonly used for delivery of soft drinks such as colas and for beer. Since these delivery trucks are often left unattended during deliveries, it is desirable to provide a locking mechanism for latching the roll-up doors in a down and closed position. For many years, the typical latching mechanism for such vehicle truck bodies has utilized a rotatable rod extending the length of the truck body above a top edge of each door. A plurality of flanges are fixedly attached to the rod so that they engage the top edge of the door when the rod is rotated through a preselected angle. A lever arm is connected to the rod and leads downward through other lever arms to a latching mechanism located at an operator level. The latching mechanism generally comprises an externally visible handle connected through an aperture in the truck body to a spring loaded mechanism either inside the truck body or in a wall of the truck body. The spring loaded mechanism utilizes a compression spring to hold the latching mechanism in either a locked or unlocked position. It has been common experience that the compression spring utilized in the latching mechanism tends to fail after repeated use. The compression spring is loaded not only by the latching mechanism but by the weight of the connecting arms extending up to the rotatable rod. This load on the compression spring causes it to lose some of its spring constant and become weakened thereby allowing the lever arm assembly to partially collapse and permit the rod to rotate through some limited angle. As the rod rotates, the flanges on the rod may lose contact with the top edge of the door so that the doors can be opened without releasing the latching mechanism. Alternatively, the loss of the spring constant may allow the rod to rotate towards the closed position when the doors are in their upright and open position so that when the doors are thereafter closed, the flange on the rod contacts and rubs against the door faces. This contact between the locking flange and the door faces not only mars the surface but can remove the finish to an extent that corrosion of the door face may occur.